The present invention relates to cutting tools for use in an apparatus for disintegrating material, such as a tree stump grinding machine.
Conventional stump grinders are disclosed in U.S. Pat. Nos. 5,279,345 and 5,497,815 for example. As shown in FIG. 1, a typical tree stump grinding machine comprises a rotatable wheel 1 having a plurality of cutting assemblies mounted thereon. The cutting assemblies are arranged in groups, each group extending in a generally helical pattern relative to the axis of rotation. Each cutting assembly comprises a pair of cutter units 2, 2xe2x80x2 disposed on respective sides 8 of the wheel and aligned with one another in a direction parallel to the axis of rotation. The wheel is rotated while adjacent to the stump and the cutter teeth are moved into contact with the stump. As a result, the stump is gradually disintegrated.
A typical cutter unit 2 or 2xe2x80x2 comprises a tooth composed of a steel shaft 3 that carries a carbide cutting tip 4. The shaft is attached to the wheel by a steel body 5 known as a xe2x80x9cpocketxe2x80x9d that is bolted to the wheel. The pockets are usually so large that the relatively smaller cutting tips are unable to cut away enough of the stump to create a space sufficiently large for the pockets to pass through. Also, the distance from the carbide cutting tip to the outside pocket surface 6, as measured in a direction perpendicular to the respective side 8 of the wheel, may be insufficient to allow uncut material (such as small rocks) and cut debris to pass freely rearward past the pocket. This uncut material and cut debris creates friction and drag between the pockets and the stump being worked which robs horsepower from the grinding operation.
The pocket 5 is made thick to provide ample strength, and a front edge 9 of the pocket is vulnerable to impact against rocks which lends to fatigue and finally breaking of both the pockets and the mounting bolts. The edge also adds more frictional resistance to the rotating wheel.
Another problem is that the shank 3 of each cutting tooth extends out from the pocket to support the carbide tip and thus increases the stress on the mounting bolts. The longer the shank, the more radial leverage is exerted on the pocket and bolts. When the carbide tip on the end of the shank hits a rock, a heavy shock load is transmitted which can sheer the mounting bolts.
A further problem is that the weight of the thick pocket is gradually reduced as a result of abrasion of the pocket caused by the friction of the pocket against the stump. After time, one or more of these worn pockets may need to be replaced. The new pockets will be heavier which can easily cause the wheel to become unbalanced, causing severe vibration problems.
Yet another problem with the currently used pockets is caused by the carbide tip being offset from the mounting portion of the pocket in a radial direction with respect to the axis of rotation. Thus, during a stump-cutting operation, the pockets situated near the top of the stump, i.e., the pockets mounted closest to the center of the wheel, will not have a path cleared for them in the stump surface as the wheel is advancing toward the stump in a direction parallel to axis of rotation (i.e., direction C in FIG. 1). That can prevent the wheel from advanced farther into the stump.
Another problem with the currently used pockets is that the operator must loosen or remove both bolts to replace each of the cutting teeth, which is time consuming.
A further problem with currently used pockets and tool systems is that all pockets and shanks on one side of the wheel are configured as mirror images of the pockets and cutting teeth on the other side. That is, different pockets and shanks must be used on each side of the wheel, which requires the operator to maintain a large inventory of all the pockets and cutting teeth for field replacement.
The present invention relates to a cutting apparatus which comprises a cutting wheel, and a plurality of cutting assemblies mounted on the cutting wheel. The cutting wheel is adapted to be driven about a center axis and includes a pair of side surfaces and an outer peripheral surface interconnecting the side surfaces. The cutting assemblies are mounted in generally circumferentially spaced relationship. Each cutting assembly comprises first and second pockets, a pair of cutting teeth, and a pair of fasteners. The first and second pockets are disposed on respective ones of the side surfaces. Each pocket includes a body having a leading end and a trailing end with reference to a direction of rotation of the cutting wheel. A leading through-hole and a trailing through-hole extend through the pocket. The leading end trailing through-holes of each pocket are aligned with respective leading end trailing through-holes of the other pocket and are aligned with respective mounting holes extending through the cutting wheel. Each of the cutting teeth includes a shank having first and second ends. The first end has an enlarged head with a hard cutting tip disposed thereon. One of the cutting teeth extends through the aligned leading through-holes of the first and second pockets, and the other cutting tooth extends through the aligned trailing through-holes of the first and the second pockets. The cutting teeth extend in mutually opposite directions, wherein the cutting elements are disposed at respective side surfaces of the cutting wheel. Each tooth is mounted against rotation relative to its respective pocket. The fasteners are attached to respective ones of the cutting teeth adjacent the second ends thereof. The enlarged head and the fastener of each tooth cooperate to clamp both of the first and second pockets against respective side surfaces of the cuffing wheel.
The invention also relates to the pocket, per se. That is, the pocket comprises a metal body having first and second sides and first and second through-holes extending through the body from the first side to the second side. The first through-hole is of circular cross-section and has a counter bore formed in the first side of the body. The second through-hole is of non-circular cross-section whose shortest dimension is no shorter than a diameter of the first through-hole. The second through-hole has a recess formed in the first side of the body.
The invention also relates to a stump cutter tooth adapted for use on a rotary stump-cutting wheel. The tooth comprises a shank which defines an axis and has first and second axially spaced ends. An external screw thread is disposed at the first end, and a seat is disposed at the second end. A cutting insert is brazed in the seat and is formed of a harder material than the shank. The second end further includes an enlargement disposed axially inwardly of the seat. The enlargement is of larger cross section than the shank and has a portion of non-circular cross section.